Japanese Patent Application Laid Open No. H8-275096 discloses a projector apparatus equipped with a lamp serving as a light source and an optical system having such elements as a polarization prism substrate, polarization plates, liquid crystal panels (LCPs), and a projection lens, all housed in a casing. Provided on a wall of the casing is an exhaust unit adapted to create an air flow inside the casing to suppress temperature rise in the casing.
Since the exhaust unit is orientated to the hot lamp so as to inspire air heated by the lamp, the air discharged from the exhaust unit is heated to a high temperature, which makes the user of the projector unpleasant when he is exposed to the hot air. Hence, in order to lower the temperature of the exhausted air, the exhaust fan of the exhaust unit must be operated at a high speed, which in turn creates a bothering noise. Moreover, a multiplicity of fans other than the exhaust fan are installed in some instance, where those fans create and leak unpleasant noises even if they are operated at low speed, since they are usually located at peripheral corners of the apparatus. Furthermore, the increase in number of the fans and related manufacturing steps results in additional assembly cost, which inevitably raises the cost of the apparatus.